The old folks were still thinking Bela Lugosi; we were thinking 'Deranged.'

Ask any Halloween aficionado what’s the edgiest haunted house in the New Orleans area and chances are they’ll say The House of Shock. For 20 years, the hair-raising labyrinth has enjoyed notoriety based on its gut-flopping gruesomeness, no-holds-barred religious irreverence, in-your-face theatricality and hellish pyrotechnics.

The House of Shock haunted house hit by Hurricane IsaacGet a rare daylight glimpse of "The House of Shock" haunted house near New Orleans with co-founders Ross Karpelman, Jay Gracianette and Steve Joseph as they discuss the 20-year-old landmark's controversial history and lead a tour of damage cause by Hurricane Isaac. Look for a detailed story titled "The House of Shock haunted house celebrates 20 years of horror" on NOLA.com.

There was a time when concerned citizens called for its closure because of its pseudo-satanic imagery.

At the two-decade mark, however, the attraction seems to have reached a plateau of cultural respectability. On opening night tonight, “The House of Shock” will team with the venerable Zulu Carnival organization to raise money for Toys for Tots.

On a recent trip to “The House of Shock,” which stands in the shadow of the skeletal Huey P. Long Bridge in an industrial section of Jefferson, three of the original co-founders, Ross Karpelman, Jay Gracianette and Steve Joseph provided a tour of the damage done by Hurricane Isaac to the two-story Gothic outdoor stage and the nearby faux cemetery.

Twisted plastic brick panels, bent plywood and broken foam shapes were piled in a heap. The work necessary to undo Isaac’s damage has tightened the noose on the attraction’s looming opening day deadline today, but the partners said they’d be ready.

The House of Shock

What: An intensely frightening, irreverent haunted house tour, with an outdoor festival featuring nightly live music and concessions. Not for young children or the easily frightened.

Where: 319 Butterworth St. in Jefferson, near the foot of the Huey P. Long Bridge.

On top of that, they listed new ghastly gimmicks that await visitors this weekend, including a mechanical bull-like giant spider ride, a zip line to allow costumed banshees to fly over the crowd, remote-control air cannons to jolt unsuspecting visitors and a meat processing plant/torture chamber theme room.

Reflecting on the sometimes contentious history of “The House of Shock,” Joseph said that sometime in the 1990s, a religiously sensitive woman appeared on the television news to take exception to the haunted house’s themes, and school kids were given notes that warned parents of its apparent evils.

“At the end of the day, that makes kids want to go all the more,” Joseph said.

He recalled that a Jefferson Parish councilman vowed that he’d shut it down if he found it offensive, but after media attention sparked a free speech debate, the public apparently came to accept that the demonic disrespectfulness practiced at “The House of Shock” was only make-believe.

Karpelman said that more explicit horror films such as “The Exorcist” and “The Texas Chain Saw Massacre” were setting a new gore standard when House of Shock opened in 1992. So to sufficiently shock audiences, they had to raise the ante.

“The old folks were still thinking Bela Lugosi; we were thinking ‘Deranged,’ ” Karpelman said, referring to a cult slasher movie.

The partners, who were in their mid-20s at the time, also wanted to emulate the dark personae of rock heroes such as Alice Cooper and Ozzy Osbourne. Karpelman, Gracianette and Joseph shared a love of and background in playing heavy metal music. Even now, when Karpelman’s not helping manage “The House of Shock,” he works as a rock ’n’ roll roadie. Joseph specializes in pyrotechnic displays for rock shows from Nickelback to the Rolling Stones.

“We’re a rock ’n’ roll haunted house,” Gracianette said.

Like any respectable rock ’n’ roll group, “The House of Shock” partnership has a legendary breakup in its past. The fourth founder, Phil Anselmo, frontman for the arena-filling metal band Pantera, split from the attraction in 1999. In a 2011 story by Times-Picayune / Nola.com music writer Keith Spera, Anselmo cryptically described the schism as a “sour subject.”

“He was a huge part of the starting of ‘The House of Shock,’” Karpelman said. “But as his career furthered, he found he had less time to dedicate to the project.”

The first incarnation of the haunted house was in Gracianette’s grandparents’ backyard and drew about 200 visitors. Now, almost 400 volunteers dress up to frighten and amuse 20,000 visitors.

In front of the warehouse warren of horrors, a slightly more family-friendly free Halloween festival is held with concessions, a bar, nightly music, sideshow acts and pre-tour theatrics. Before entering, tour-takers are treated to a five-minute malevolent melodrama that pits evil against evil for cosmic domination, complete with arena rock hellfire.

And while there is no minimum age to enter the attraction, parents should note that the experience features theatrical crucifixion, mutilation, strangulation, blood-letting, demon worship and other necrotic nightmares.

There are kids who leave laughing and adults who leave crying, Joseph said. As per contemporary haunted house custom, everyone leaves with chainsaw wielding maniacs in noisy pursuit.